Vapor compression system including a swiveling compressor

ABSTRACT

A refrigeration system includes a fluid circuit circulating a refrigerant in a closed loop. The fluid circuit has operably disposed therein, in serial order, a compressor, a first heat exchanger, an expansion device and a second heat exchanger. The compressor is pivotable about an axis. The compressor has a first part and a second part slidably coupled to the first part. A linkage includes a cyclically movable element. A linking element is attached to the second part of the compressor and is pivotably coupled to the cyclically movable element such that the linking element follows movement of the cyclically movable element to thereby slide the second part of the compressor relative to the first part of the compressor and pivot the compressor about the axis.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to vapor compression apparatus and, moreparticularly, to vapor compression apparatus that may be used inrefrigeration systems.

2. Description of the Related Art

Vapor compression apparatus are used in a variety of applicationsincluding heat pump, air conditioning, and refrigeration systems. Suchsystems may include either rotary compressors or linear compressors. Ina rotary compressor, refrigerant may be compressed in a chamber definedbetween a fixed outer housing and a rotating inner core. In a linearcompressor, refrigerant may be compressed in a cylinder that slidinglyreceives a piston that reciprocates with a linear motion in and out ofthe cylinder.

One problem with linear compressors is that it may be difficult tocontrol the position of the moving part, e.g., the piston, which mayresult in the piston hitting a stationary part, e.g., hitting the bottomof the cylinder at the bottom dead center of the piston stroke. Suchcollisions may result in damage to the piston, the cylinder, and/or therod that drives the piston. It is known to provide a linear compressorwith a stopper in order to prevent the piston from hitting a stationarypart. The stopper may be in the form of a spring in the piston cup orelectronics for sensing the position of the piston and controlling themovement of the piston, for example. A stopper adds to the cost andcomplexity of the compression system, however.

Another problem with linear compressors is that reducing the coolingcapacity may result in lower efficiency. For example, the coolingcapacity may be reduced by shortening the stroke of the piston. When thestroke is shortened, the piston still reaches the outermost position ofthe stator. Thus, in order to shorten the stroke, one must eliminate aportion of the stroke in which the piston is near the middle of themotor and in which the motor is most efficient. p Yet another problemwith linear compressors is that a pivoting joint that may be providedbetween the piston and a rod that drives the piston is subject to highlevels of stress and is thus susceptible to failure. More particularly,one end of the rod may be rotated by a rotary motor, while the oppositeend of the rod is pivotably attached to the piston. Operation of therotary motor results in the piston being reciprocated, i.e., movedlinearly, in and out of the cylinder. The forces required to both pushthe piston into the cylinder and pull the piston out of the cylinder aretransferred from the rod to the piston via the pivoting joint. In someapplications, such as when carbon dioxide is used as the refrigerant,the piston diameter tends to be small. Thus, the pivoting joint betweenthe rod and the piston must be correspondingly small. A small pivotingjoint is even less able to withstand the stresses that are imposed uponthe joint during operation.

A further problem particular to the pivoting joint between the pistonand the rod is that the mass of the pivoting joint adds to thereciprocating motion inertia of the oscillating piston. Thus, the addedmass of the pivoting joint adds to the stresses placed on the motor, onthe rod, and on any other linking elements associated therewith.

A still further problem particular to the pivoting joint between thepiston and the rod is that the pivoting joint is difficult formaintenance personnel to access. That is, the position of the pivotingjoint between the rod and the piston may be such that it is difficultfor maintenance personnel to lubricate or replace the pivoting joint.

What is needed in the art is a linear compressor system that overcomesthe problems of known linear compressors. More particularly, what isneeded is a linear compressor system that does not require expensivecomponents to prevent the moving parts from hitting the stationaryparts, that can operate at high efficiency when capacity has beenreduced, and that is not subject to the problems associated withpivoting joints between rods and pistons.

SUMMARY OF THE INVENTION

The present invention provides a linear vapor compression system thatmay include a compressor that is pivotable relative to a fixedstructure. A connecting arm that drives the piston of the compressor maybe pivotably connected to a cyclically movable element that drives theconnecting arm. The connecting arm may follow the cyclical movement tothereby reciprocate the piston in a cylinder of the compressor whilecausing the compressor to pivot relative to the fixed structure.

The invention comprises, in one form thereof, a refrigeration systemincluding a fluid circuit circulating a refrigerant in a closed loop.The fluid circuit has operably disposed therein, in serial order, acompressor, a first heat exchanger, an expansion device and a secondheat exchanger. The compressor is pivotable about an axis. Thecompressor has a first part and a second part slidably coupled to thefirst part. A linkage includes a cyclically movable element. A linkingelement is attached to the second part of the compressor and ispivotably coupled to the cyclically movable element such that thelinking element follows movement of the cyclically movable element tothereby slide the second part of the compressor relative to the firstpart of the compressor and pivot the compressor about the axis.

The present invention comprises, in another form thereof, a vaporcompression apparatus including a compressor having a first part and asecond part slidably coupled to the first part. The compressor ispivotable about an axis. A linkage includes a cyclically movableelement. A linking element is attached to the second part of thecompressor and is pivotably coupled to the cyclically movable elementsuch that the linking element follows movement of the cyclically movableelement to thereby slide the second part of the compressor relative tothe first part of the compressor and pivot the compressor about theaxis. A motor is drivingly coupled to the cyclically movable element.

The present invention comprises, in yet another form thereof, a vaporcompression apparatus including a plurality of compressors. Each of thecompressors has a respective piston slidably coupled to a respectivecylinder. Each of the compressors is pivotable about a respective swivelaxis. A linkage includes a rod defining a longitudinal axis. Each of aplurality of connecting arms is attached to a respective one of thepistons and is pivotably coupled to the rod such that each of theconnecting arms follows movement of the rod along the longitudinal axisto thereby slide each respective piston relative to each respectivecylinder and pivot each respective compressor about each respectiveswivel axis.

An advantage of the present invention is that expensive components arenot required to prevent the moving parts of the compressor from hittingthe stationary parts.

Another advantage is that the compressor can operate at high efficiencyeven when the capacity of the compressor has been reduced.

Yet another advantage is that a pivoting joint between the rod and thepiston is not required. Rather, a pivoting joint is provided between thecylinder and a fixed structure. Such a pivoting joint between thecylinder and a fixed structure is not reciprocated along with thepiston, and is not subject to the forces required to push the pistoninto the cylinder and pull the piston out of the cylinder. Further, thepivoting joint does not add to the reciprocating motion inertia of theoscillating piston, and thus does not add to the stresses placed on themotor, on the rod, and on any other linking elements associatedtherewith. Moreover, since the pivoting joint is not disposed on thepiston, the size of the joint is not limited, and the joint can beprovided with a more sturdy construction. Yet another advantage of thepivoting joint is that it is relatively easy for maintenance personnelto access.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features and objects of this invention,and the manner of attaining them, will become more apparent and theinvention itself will be better understood by reference to the followingdescription of an embodiment of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1 is a schematic diagram of one embodiment of a refrigerationsystem of the present invention;

FIG. 2 a is a schematic side view of one embodiment of the vaporcompression apparatus of the refrigeration system of FIG. 1 in a firstposition;

FIG. 2 b is a schematic side view of the vapor compression apparatus ofFIG. 2 a in a second position;

FIG. 2 c is a schematic side view of the vapor compression apparatus ofFIG. 2 a in a third position;

FIG. 3 a is a schematic view of a first stage of a compression cycle ofthe vapor compression apparatus of FIG. 1;

FIG. 3 b is a schematic view of a second stage of a compression cycle ofthe vapor compression apparatus of FIG. 1;

FIG. 3 c is a schematic view of a third stage of a compression cycle ofthe vapor compression apparatus of FIG. 1;

FIG. 3 d is a schematic view of a fourth stage of a compression cycle ofthe vapor compression apparatus of FIG. 1;

FIG. 4 a is an schematic overhead view of another embodiment of a vaporcompression apparatus of the present invention;

FIG. 4 b is a schematic overhead view of yet another embodiment of avapor compression apparatus of the present invention; and

FIG. 5 is a schematic side view of another embodiment of a vaporcompression apparatus of the present invention.

Corresponding reference characters indicate corresponding partsthroughout the several views. Although the exemplification set outherein illustrates an embodiment of the invention, the embodimentdisclosed below is not intended to be exhaustive or to be construed aslimiting the scope of the invention to the precise form disclosed.

DESCRIPTION OF THE PRESENT INVENTION

FIG. 1 illustrates one embodiment of a refrigeration system 10 of thepresent invention including a fluid circuit circulating refrigerant in aclosed loop. In the illustrated example, a two stage vapor compressionapparatus 11 is employed having a first compressor 12 and a secondcompressor 14 that are in fluid communication with each other. The firstcompressor 12 receives the refrigerant on an inlet port 13 a andcompresses the refrigerant from a suction pressure to an intermediatepressure before expelling the refrigerant on an outlet port 15 a. Anintercooler 16 is positioned between the first and second compressorsand cools the intermediate pressure refrigerant. The second compressor14 then receives the refrigerant on an inlet port 13 b and compressesthe refrigerant from the intermediate pressure to a discharge pressurebefore expelling the refrigerant on an outlet port 15 b. Inlet ports 13a, 13 b and outlet ports 15 a, 15 b may each include a respectiveone-way valve (not shown), sometimes referred to as a “check valve”,that allows the refrigerant to flow through the port in only onedirection, i.e., in the direction indicated in FIG. 1. The refrigerantis then cooled in a gas cooler 18 before having its pressure reduced byexpansion device 22. The refrigerant then enters evaporator 24 where itis boiled and cools a secondary medium, such as air, that may be used,for example, to cool a refrigerated cabinet. The refrigerant dischargedfrom the evaporator 24 enters the first compressor 12 to repeat thecycle.

As shown in FIG. 2 a, compressors 12, 14 include respective cylinders 26a, 26 b slidably coupled to respective pistons 28 a, 28 b. Pistons 28 a,28 b are slidable within cylinders 26 a, 26 b in directions indicated byrespective double arrows 29 a, 29 b. By sliding into cylinders 26 a, 26b, pistons 28 a, 28 b compress the refrigerant that is in respectivechambers 30 a, 30 b that are defined between the pistons and cylinders.

Each of cylinders 26 a, 26 b is pivotably coupled to a respective fixedstructure 31 a, 31 b by a respective pivoting joint 32 a, 32 b. Pivotingjoints 32 a, 32 b define respective swivel axes 34 a, 34 b extendinginto the page of FIG. 2 a. Compressors 12, 14 are pivotable aboutrespective axes 34 a, 34 b in directions indicated by double arrows 36a, 36 b, respectively.

In addition to compressors 12, 14, vapor compression apparatus 11includes a motor 38 and a linkage 40 for driving compressors 28 a, 28 bin and out of cylinders 26 a, 26 b. In the embodiment of FIG. 2 a, motor38 is shown in the form of a linear motor that is configured to drive ashaft along a longitudinal axis 42. More particularly, linear motor 38is drivingly coupled to a rod 44 of linkage 40 such that motor 38 mayreciprocate rod 44 along the longitudinal axis 42 in opposite directionsindicated by arrows 46, 48. Rod 44 may be at least partially formed of amagnetic or magnetizable material such that the changing magnetic fieldproduced by magnets 50 a, 50 b of motor 38 can selectively cause rod 44to move in one of directions 46, 48. Magnets 50 a, 50 b may beelectromagnets or permanent magnets. In order for a force to be exertedon rod 44 in one of directions 46, 48 rather than in the other ofdirections 46, 48 at a given point in time, rod 44 may have sections ofdifferent magnetic polarity along its length. Thus, rod 44 may be movedin one of directions 46, 48. Alternatively, rod 44 may have differentamounts of magnetic or magnetizable material along its length. Asanother possibility, the upper end of rod 44 may be disposed betweenmagnets 50 a, 50 b, such that most of rod 44 is disposed below magnets50 a, 50 a, thus enabling magnets 50 a, 50 b to selectively attract rod44 in direction 48 or repel rod 44 in direction 46. The force of gravityon rod 44 may be negligible in comparison to the magnetic force exertedon rod 44 by magnets 50 a, 50 b.

Linkage 40 also includes two linking elements in the form of connectingarms 52 a, 52 b having respective ends that are pivotably andindependently coupled to rod 44 via a pivoting joint 54. Pivoting joint54 defines a pivot axis 56 oriented into the page of FIG. 2 a aboutwhich connecting arms 52 a, 52 b are pivotable relative to rod 44 in thedirections indicated by double arrow 58. Axis 56 may be perpendicular todirections 46, 48. Opposite ends of connecting arms 52 a, 52 b may befixedly attached to respective pistons 28 a, 28 b. For example,connecting arms 52 a, 52 b may be welded, bonded, attached withfasteners, or integrally formed with pistons 28 a, 28 b.

In order to balance out the lateral resistive force of compressors 12,14 on rod 44, and thereby inhibit rod 44 from becoming misaligned inmotor 38, connecting arms 52 a, 52 b may be disposed 180 degrees apartfrom each other relative to longitudinal axis 42. That is, connectingarms 52 a, 52 b may be arranged axi-symmetrically about axis 42. Thepivot axis 56 may be parallel to both pivot axes 34 a, 34 b. Thus, pivotaxes 34 a, 34 b may also be oriented parallel to each other.

FIG. 2 a may represent the uppermost position of rod 44 and pivotingjoint 54 in direction 48. Chambers 30 a, 30 b may have a maximum volumewhen vapor compression apparatus 11 is in the position of FIG. 2 a.

FIG. 2 b illustrates the bottom dead center position of vaporcompression apparatus 11 wherein pivoting joint 54 may be aligned withand/or in its position that is closest to pivoting joints 32 a, 32 b.The volumes of chambers 30 a, 30 b may be at a minimum in the positionof FIG. 2 b.

FIG. 2 c may represent the lowermost position of rod 44 and pivotingjoint 54 in direction 46. Chambers 30 a, 30 b may have a maximum volumewhen vapor compression apparatus 11 is in the position of FIG. 2 c. Itis to be understood, however, that the volume of chambers 30 a, 30 b inthe position of FIG. 2 c may be less than, equal to, or greater than thevolume of chambers 30 a, 30 b in the position of FIG. 2 a.

An advantage of the invention is that if motor 38 overshoots, therebycausing rod 44 to move in direction 48 past the position shown in FIG. 2a, or causing rod 44 to move in direction 46 past the position shown inFIG. 2 c, pistons 28 a, 28 b will merely be pulled farther out ofcylinders 26 a, 26 b. That is, pistons 28 a, 28 b will not hit orcollide with any stationary parts.

Another advantage of the invention is that magnets 50 a, 50 b may holdrod 44 in the bottom dead center position when power is not applied tomotor 38. Thus, when power is first applied to motor 38 at start up,pistons 28 a, 28 b will first be pulled out of cylinders 26 a, 26 b tothereby draw refrigerant into chambers 30 a, 30 b. The suction ofrefrigerant into chambers 30 a, 30 b requires less work than thecompression of refrigerant in chambers 30 a, 30 b. The reduced load atstart up enables the use of a less expensive motor having a smallerstart force. Moreover, the efficiency of motor 38 in actuating rod 44may be greater in the bottom dead center position.

Another advantage of vapor compression apparatus 11 starting in thebottom dead center position is that if chambers 30 a, 30 b becomeflooded with liquid refrigerant or liquid lubricant while motor 38 isnot powered, the liquid will not be compressed by pistons 28 a, 28 bupon start up. Rather, pistons 28 a, 28 b will be pulled out ofcylinders 26 a, 26 b at start up. Compressing a liquid can cause damageto a compressor mechanism, as is well known.

In operation, motor 38 may cyclically and alternatingly move rod 44 indirections 46, 48 in order to cyclically and alternatingly push and pullpistons 28 a, 28 b into and out of cylinders 26 a, 26 b. As demonstratedin FIGS. 2 a and 2 c, connecting arms 52 a, 52 b may be alternatinglyoriented at acute and obtuse angle relative to rod 44 during thecyclical movement of rod 44. As demonstrated in FIG. 2 b, pivoting joint54 passes through a point on longitudinal axis 42 that is closest tocylinder 26 a and that is closest to cylinder 26 b.

FIGS. 3 a through 3 d illustrate the different stages in a cycle ofvapor compression apparatus 11. There may be two compressions ofrefrigerant in chambers 30 a, 30 b per cycle.

FIG. 3 a illustrates the first of the four stages, i.e., at the start ofa cycle, where rod 44 has come to a rest after moving in direction 48and is beginning to move in direction 46. Suction of refrigerant intochambers 30 a, 30 b has been completed, and compression of therefrigerant within chambers 30 a, 30 b is about to start. Pistons 28 a,28 b are fully withdrawn from cylinders 26 a, 26 b to thereby maximizethe volume of chambers 30 a, 30 b. The movement of rod 44 in direction46 causes connecting arms 52 a, 52 b to rotate about pivoting joint 54.As pivoting joint 54 moves in direction 46, pistons 28 a, 28 b movefarther into cylinders 26 a, 26 b to thereby compress the refrigerant inchambers 30 a, 30 b. As the pressure in chambers 30 a, 30 b increasespast a threshold value, one-way valves (not shown) that are fluidlyconnected to outlets 15 a, 15 b are forced open, and the compressedrefrigerant vapor is expelled from chambers 30 a, 30 b. Cylinders 26 a,26 b may rotate about respective swivel axes 34 a, 34 b in order toaccommodate the changing orientation of connecting arms 52 a, 52 b. Moreparticularly, from the viewpoint of FIG. 2 a, cylinder 26 a may rotateclockwise, and cylinder 26 b may rotate counterclockwise.

FIG. 3 b illustrates the second of the four stages where vaporcompression apparatus 11 is at bottom dead center. The compression ofrefrigerant within chambers 30 a, 30 b has been completed, thecompressed refrigerant has been expelled, and suction of additionalrefrigerant into chambers 30 a, 30 b is about to start. Pistons 28 a, 28b are fully inserted into cylinders 26 a, 26 b to thereby minimize thevolume of chambers 30 a, 30 b. The refrigerant within cylinders 26 a, 26b has been fully compressed and expelled from chambers 30 a, 30 b.Further movement of rod 44 and pivoting joint 54 in direction 46 causespistons 28 a, 28 b to be pulled out of cylinders 26 a, 26 b to therebydraw refrigerant vapor into chambers 30 a, 30 b through inlets 13 a, 13b. As the vacuum pressure in chambers 30 a, 30 b decreases past athreshold value, one-way valves (not shown) that are fluidly connectedto inlets 13 a, 13 b are forced open, and refrigerant vapor at nearatmospheric pressure may be drawn into chambers 30 a, 30 b. Cylinders 26a, 26 b may continue to rotate about respective swivel axes 34 a, 34 bin order to accommodate the changing orientation of connecting arms 52a, 52 b.

FIG. 3 c illustrates the third of the four stages, where rod 44 has cometo a rest after moving in direction 46 and is beginning to move indirection 48. Suction of refrigerant into chambers 30 a, 30 b has beencompleted, and compression of the refrigerant within chambers 30 a, 30 bis about to start. Pistons 28 a, 28 b are fully withdrawn from cylinders26 a, 26 b to thereby maximize the volume of chambers 30 a, 30 b. Themovement of rod 44 in direction 48 causes connecting arms 52 a, 52 b torotate about pivoting joint 54. As pivoting joint 54 moves in direction48, pistons 28 a, 28 b move farther into cylinders 26 a, 26 b to therebycompress the refrigerant in chambers 30 a, 30 b. As the pressure inchambers 30 a, 30 b increases past a threshold value, one-way valves(not shown) that are fluidly connected to outlets 15 a, 15 b are forcedopen, and the compressed refrigerant vapor is expelled from chambers 30a, 30 b. Cylinders 26 a, 26 b may rotate about respective swivel axes 34a, 34 b in directions opposite to their directions in the first twostages in order to accommodate the changing orientation of connectingarms 52 a, 52 b. More particularly, from the viewpoint of FIG. 2 c,cylinder 26 a may rotate counterclockwise, and cylinder 26 b may rotateclockwise.

FIG. 3 d illustrates the fourth of the four stages where vaporcompression apparatus 11 is again at bottom dead center. In contrast tothe second stage illustrated in FIG. 3 b, the movement of rod 44 is indirection 48. The compression of refrigerant within chambers 30 a, 30 bhas been completed, the compressed refrigerant has been expelled, andsuction of additional refrigerant into chambers 30 a, 30 b is about tostart. Pistons 28 a, 28 b are fully inserted into cylinders 26 a, 26 bto thereby minimize the volume of chambers 30 a, 30 b. The refrigerantwithin cylinders 26 a, 26 b has been fully compressed and expelled fromchambers 30 a, 30 b. Further movement of rod 44 and pivoting joint 54 indirection 48 causes pistons 28 a, 28 b to be pulled out of cylinders 26a, 26 b to thereby draw refrigerant vapor into chambers 30 a, 30 bthrough inlets 13 a, 13 b. As the vacuum pressure in chambers 30 a, 30 bdecreases past a threshold value, one-way valves (not shown) that arefluidly connected to inlets 13 a, 13 b are forced open, and refrigerantvapor at near atmospheric pressure may be drawn into chambers 30 a, 30b. Cylinders 26 a, 26 b may continue to rotate about respective swivelaxes 34 a, 34 b in order to accommodate the changing orientation ofconnecting arms 52 a, 52 b. At the end of the fourth stage, vaporcompression apparatus 11 is again in the position of FIG. 3 a, and thefirst stage of a subsequent cycle may begin.

As described above, refrigerant in chambers 30 a, 30 b may be compressedtwice per cycle. However, in other embodiments, refrigerant in chambers30 a, 30 b may be compressed only once per cycle. In one embodiment,vapor compression apparatus 11 may oscillate between the position ofFIG. 2 a and the position of FIG. 2 b. That is, as soon as rod 44 hasmoved far enough in direction 46 to reach the bottom dead centerposition of FIG. 2 b, rod 44 begins to move back in direction 48. Thus,vapor compression apparatus 11 undergoes a two stage cycle in whichrefrigerant compression occurs as rod 44 moves in direction 46, andrefrigerant suction occurs as rod 44 moves in direction 48.

In another embodiment in which refrigerant is compressed only once percycle, vapor compression apparatus 11 may oscillate between the positionof FIG. 2 b and the position of FIG. 2 c. That is, as soon as rod 44 hasmoved far enough in direction 48 to reach the bottom dead centerposition of FIG. 2 b, rod 44 begins to move back in direction 46. Thus,vapor compression apparatus 11 undergoes a two stage cycle in whichrefrigerant compression occurs as rod 44 moves in direction 48, andrefrigerant suction occurs as rod 44 moves in direction 46.

The one-compression-per-cycle embodiments described above have the sameadvantage as the two compression per cycle embodiments in that if motor38 overshoots, thereby causing rod 44 to move in direction 48 past theposition shown in FIG. 2 a, or causing rod 44 to move in direction 46past the position shown in FIG. 2 c, pistons 28 a, 28 b will merely bepulled farther out of cylinders 26 a, 26 b. That is, pistons 28 a, 28 bwill not hit or collide with any stationary parts.

In other embodiments, there may be more than two compressors andcorresponding connecting arms pivotably coupled to the rod. FIG. 4 aillustrates an embodiment of a vapor compression apparatus 111 in whichthree compressors 112 a, 112 b and 112 c are axi-symmetrically arrangedaround a longitudinal axis 142 of a rod 144 driven by a linear motor138. Each piston 128 a, 128 b, 128 c may be fixedly attached to arespective connecting arm 152 a, 152 b, 152 c that is pivotably coupledto rod 144. Angles θ₁, θ₂ and θ₃ between the connecting arms may each beapproximately 120 degrees. Other aspects of vapor compression apparatus111 may be substantially similar to those of vapor compression apparatus11, and thus are not discussed in detail herein.

FIG. 4 b illustrates an embodiment of a vapor compression apparatus 211in which four compressors 212 a, 212 b, 212 c and 212 d areaxi-symmetrically arranged around a longitudinal axis 242 of a rod 244driven by a linear motor 238. Each piston 228 a, 228 b, 228 c, 228 d maybe fixedly attached to a respective connecting arm 252 a, 252 b, 252 c,252 d that is pivotably coupled to rod 244. Angles θ₁, θ₂, θ₃ and θ₄between the connecting arms may each be approximately 90 degrees.Alternatively, angles θ₁, θ₂, θ₃ and θ₄ may have some otheraxi-symmetrical set of values, such as 30 degrees, 120 degrees, 30degrees, and 120 degrees, respectively, for example. Other aspects ofvapor compression apparatus 211 may be substantially similar to those ofvapor compression apparatus 11, and thus are not discussed in detailherein.

Another embodiment of a vapor compression apparatus 311 is illustratedin FIG. 5. In contrast to previously discussed vapor compressionapparatus that include linear motors, vapor compression apparatus 311includes a rotary motor 338. Motor 338 is drivingly coupled to acyclically movable element in the form of a rotating disc 344 that maybe rotated about a rotational axis 342 in either of the directionsindicated by double arrow 347. Rotating disc 344 may include a pivotingjoint 354 that is pivotably and independently coupled to each ofconnecting arms 352 a, 352 b. Connecting arms 352 a, 352 b may befixedly attached to respective pistons 328 a, 328 b. As disc 344rotates, pistons 328 a, 328 b are cyclically pushed into and pulled outof respective cylinders 326 a, 326 b. Cylinders 326 a, 326 b areattached to respective pivoting joints 332 a, 332 b such that cylinders326 a, 326 b may swivel in directions indicated by respective doublearrows 336 a, 336 b in order to accommodate the changing orientations ofconnecting arms 352 a, 352 b. Other aspects of vapor compressionapparatus 311 may be substantially similar to those of vapor compressionapparatus 11, and thus are not discussed in detail herein.

When multiple compressors are used in conjunction with a linear motor,the compressors have been shown herein as being disposed atapproximately the same locations along the longitudinal axis of the rod.However, it is also possible for the compressors to be placed atdifferent positions along the rod's longitudinal axis.

The pivoting joints on which the compressor cylinders swivel have beenshown herein as being attached near the middle of the end walls of thecylinders. However, it is to be understood that the pivoting joints canbe attached at any point on the cylinders, including on the annular sidewall. Further, the swivel axes defined by the pivoting joints need notbe closely adjacent the cylinders. Rather, the swivel axes may befarther from the cylinders than as shown in the drawings.

The inlet ports and outlet ports of the cylinders have been shownherein, for ease of illustration, as being disposed on the annular sidewalls of the cylinders. However, the inlet ports and outlet ports couldalso be located on the end walls of the cylinders.

The connecting arms have been shown herein as being fixedly attached tothe pistons, while the cylinders are pivotably coupled to a fixedstructure. However, it is also within the scope of the present inventionfor the connecting arms to be fixedly attached to the cylinders, withthe pistons being pivotably coupled to a fixed structure.

In the embodiments shown herein, the compressors include piston andcylinder mechanisms. However, it is to be understood that the presentinvention can also be used in conjunction with different types ofcompression mechanisms.

The linear motor embodiments shown herein also disclose the vaporcompression apparatus reaching a bottom dead center position in thecycle whereat the pistons are inserted into the cylinders to a maximumdegree. However, it is also within the scope of the present inventionfor the connecting arms to oscillate between two positions such that thepistons are never fully inserted into the cylinders. For example, theconnecting arms may oscillate between a first position in which theconnecting arms form a 30 degree angle with the rod and a secondposition in which the connecting arms form a 60 degree angle with therod.

While this invention has been described as having an exemplary design,the present invention may be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles.

1. A refrigeration system comprising: a fluid circuit circulating arefrigerant in a closed loop, the fluid circuit having operably disposedtherein, in serial order, a compressor, a first heat exchanger, anexpansion device and a second heat exchanger, the compressor beingpivotable about an axis, the compressor having a first part and a secondpart slidably coupled to the first part; and a linkage including: acyclically movable element; and a linking element attached to the secondpart of the compressor and pivotably coupled to the cyclically movableelement such that the linking element follows movement of the cyclicallymovable element to thereby slide the second part of the compressorrelative to the first part of the compressor and pivot the compressorabout the axis.
 2. The system of claim 1 wherein the axis about whichthe compressor is pivotable comprises a first axis, the linking elementbeing pivotable about a second axis relative to the cyclically movableelement, the second axis being substantially parallel to the first axis.3. The system of claim 2 wherein the movement of the cyclically movableelement is in a direction substantially perpendicular to the secondaxis.
 4. The system of claim 2 wherein the compressor comprises a firstcompressor, the fluid circuit having a second compressor, the linkingelement comprising a first linking element, the linkage including asecond linking element attached to the second compressor and pivotablycoupled to the cyclically movable element such that the second linkingelement follows movement of the cyclically movable element to therebyslide a second part of the second compressor relative to a first part ofthe second compressor and pivot the second compressor about a thirdaxis.
 5. The system of claim 4 wherein the third axis is substantiallyparallel to each of the first axis and the second axis.
 6. The system ofclaim 1 wherein the first part of the compressor comprises a cylinder,and the second part of the compressor comprises a piston.
 7. The systemof claim 1 wherein the linking element comprises a connecting arm, andthe cyclically movable element comprises a rod.
 8. The system of claim 1further comprising a motor drivingly coupled to the cyclically movableelement.
 9. The system of claim 8 wherein the motor comprises a linearmotor.
 10. The system of claim 8 wherein the motor comprises a rotarymotor.
 11. The system of claim 1 wherein the linking element is fixedlyattached to the second part of the compressor.
 12. A vapor compressionapparatus comprising: a compressor having a first part and a second partslidably coupled to the first part, the compressor being pivotable aboutan axis; a linkage including: a cyclically movable element; and alinking element attached to the second part of the compressor andpivotably coupled to the cyclically movable element such that thelinking element follows movement of the cyclically movable element tothereby slide the second part of the compressor relative to the firstpart of the compressor and pivot the compressor about the axis; and amotor drivingly coupled to the cyclically movable element.
 13. Theapparatus of claim 12 wherein the axis about which the compressor ispivotable comprises a first axis, the linking element being pivotableabout a second axis relative to the cyclically movable element, thesecond axis being substantially parallel to the first axis.
 14. Theapparatus of claim 13 wherein the movement of the cyclically movableelement is in a direction substantially perpendicular to the secondaxis.
 15. The apparatus of claim 14 wherein the compressor comprises afirst compressor, the fluid circuit having a second compressor, thelinking element comprising a first linking element, the linkageincluding a second linking element attached to the second compressor andpivotably coupled to the cyclically movable element such that the secondlinking element follows movement of the cyclically movable element tothereby slide a second part of the second compressor relative to a firstpart of the second compressor and pivot the second compressor about athird axis.
 16. The apparatus of claim 15 wherein the third axis issubstantially parallel to each of the first axis and the second axis.17. The apparatus of claim 12 wherein the first part of the compressorcomprises a cylinder, and the second part of the compressor comprises apiston.
 18. The apparatus of claim 12 wherein the linking elementcomprises a connecting arm, and the cyclically movable element comprisesa rod.
 19. The apparatus of claim 12 wherein the motor comprises alinear motor.
 20. The apparatus of claim 12 wherein the motor comprisesa rotary motor.
 21. The apparatus of claim 12 wherein the linkingelement is fixedly attached to the second part of the compressor.
 22. Avapor compression apparatus comprising: a plurality of compressors, eachof the compressors having a respective piston slidably coupled to arespective cylinder, each of the compressors being pivotable about arespective swivel axis; and a linkage including: a rod defining alongitudinal axis; and a plurality of connecting arms, each of theconnecting arms being attached to a respective one of the pistons andbeing pivotably coupled to the rod such that each of the connecting armsfollows movement of the rod along the longitudinal axis to thereby slideeach respective piston relative to each respective cylinder and pivoteach respective compressor about each respective swivel axis.
 23. Theapparatus of claim 22 wherein the compressors are in fluid communicationwith each other.
 24. The apparatus of claim 22 further comprising alinear motor coupled to the rod and configured to reciprocate the rodalong the longitudinal axis.
 25. The apparatus of claim 22 wherein eachof the connecting arms is pivotable about a respective pivot axisrelative to the rod, each of the pivot axes being substantially parallelto a respective one of the swivel axes.
 26. The apparatus of claim 25wherein the longitudinal axis is substantially perpendicular to each ofthe pivot axes.
 27. The apparatus of claim 22 wherein each of theconnecting arms is fixedly attached to a respective one of the pistons.